Conventional production of transparent originals for printing plates have previously been based on a layout. In accordance with conventional production techniques, a so-called "paste-up" is obtained by mounting the text on carriers considering the layout, and a collection film is made from the paste-up. On one or more collection films the picture reproductions are then mounted according to the layout. For multi-color printing, one film is provided for each color. The different part-colored pictures, or separations, of the same multi-color picture must be mounted extremely carefully so that the different part-color prints coincide with each other in the completed multi-color print. The collection film carrying the text should first be copied down to a film having a light sensitive material. In order to copy the pictures down to the same light sensitive film when working with positive text and pictures, a mask must be provided which has opaque parts instead of the pictures on a film. The picture mask is placed above the light sensitive film before the text is copied thereon, such that the parts of the light sensitive film which shall carry the pictures remain unexposed. The picture mask is thereafter removed, and a mask in which the sole transparent parts are the parts corresponding to the pictures is put on the light sensitive film which has already been exposed with the text, whereupon the pictures are exposed on the same time. After developing the light sensitive film, a transparent film is obtained which carries both text and pictures, and which film can be copied directly down to a printing plate which is prepared with a light sensitive layer.
The previously used method described above for the production of transparent originals or printing plates involves several disadvantages. A great degree of expert skill is necessary, for example, in order to get the different color separations of the same color picture in careful register with each other. Great care and expert skill are also necessary for the production of the necessary mask films for exposure of the pictures and text, respectively. Further, when color-separating color pictures, it is desireable to separate several pictures at the same time due to the time consuming and complicated nature of color-separation work. Therefore those several color pictures which may conveniently be separated at the same time are mounted on the same original base adjacent each other, and a number of color separation films are obtained, which mutually exactly coincide with each other and which may, considering their location on the color separation film, easily be brought to exact coincidence with each other by means of a register pin system or the like of a conventional color-separation camera. However, in the conventional production techniques described above, mounting of the color pictures according to the layout has required that the color separation films be cut into separate unit which are separately mounted on the collection film for pictures. It would be most advantageous to be able to use the color-separation films intact since not cutting them in pieces would eliminate the problems involved in mounting the color-separations exactly according to the layout, and in the mutual manual registering thereof by utilizing the exact mutual registration obtained in a color-separation camera or scanner. This advantage would obtain for whichever method is used for the copying, viz. a positive copying method or a negative copying method.